WASHINGTON - Like many Americans, Texas businessman Leo Linbeck III has grown increasingly fed up with dysfunctional government and the hyperpartisanship that has generated political gridlock and gamesmanship in the nation's capital.

This year, he's doing something most Americans cannot: The CEO of Houston-based Aquinas Companies has funneled more than $750,000 into a so-called "Super PAC" to influence elections and help challengers topple congressional incumbents from both parties and all political philosophies.

His group, the Campaign for Primary Accountability, already has helped to unseat Republican House members in Ohio and Illinois, scared one into retirement in Indiana and is hoping to make a big splash in Texas, where it is working against two Democratic and two Republican incumbents in the May 29 primary.

"We have made entrenched incumbents compete in the primary, many for the first time in a long time," said Linbeck, 50, who teaches graduate courses at the Rice and Stanford University business schools. "We've also made incumbents fear for their jobs. Congressional representatives should not have tenure. They should be on rolling two-year contracts that can be easily terminated by the voters."

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Big-time donors

Here are some of the most prominent donors to Super PACs:

Bob Perry: The Houston homebuilder has given more than $6 million to Super PACs backing Mitt Romney and Rick Perry, as well as the committee created by GOP strategist Karl Rove.

Sheldon and Miriam Adelson: The Las Vegas casino magnate and his wife gave $5 million to a pro-Newt Gingrich Super PAC when the former House speaker's campaign was running out of cash.

Foster Friess: The Wyoming businessman kept the Rick Santorum campaign afloat for months by donating $1.6 million to the Red, White and Blue Fund.

Leo Linbeck: The Houston businessman has spent more than $750,000 to build a Super PAC designed to challenge congressional incumbents from both parties.

Bill Maher: The liberal comedian donated $1 million to a Super PAC supporting President Barack Obama.

Campaigns changed

Linbeck's early Super PAC successes are further evidence of the major impact these groups, funded by wealthy individuals and corporations, have had in American politics. In just two years, this nascent political phenomenon fundamentally changed the way American campaigns operate.

In the early months of the 2012 campaign, spending by Super PACs dwarfed the amount spent by candidates and traditional political parties. As of April 12, 421 Super PACs reported total receipts of more than $159 million, according to the nonpartisan Center for Responsive Politics.

Republicans have been the major beneficiaries thus far. GOP or conservative groups have accounted for more than 80 percent of Super PAC cash accumulated since the landmark Supreme Court ruling allowing Super PACs, according to a Houston Chronicle analysis of Federal Election Commission data.

Super PAC spending helped Republicans recapture the U.S. House of Representatives and a majority of state legislatures in 2010. In this year's Republican presidential race, a Super PAC supporting Mitt Romney systematically eviscerated rivals Rick Perry, Newt Gingrich and Rick Santorum, while billionaire supporters with Super PACs kept the Gingrich and Santorum efforts alive long after their presidential campaigns ran low on funds.

The big-money infusion radically altered the financial landscape of campaigns - effectively eliminating contribution limits created by Congress after the Watergate scandal of the 1970s.

"It's an opportunity for people who have considerable wealth to get an advantage," said Candice Nelson, an American University political science professor. "In some ways, we're back to the days before (post-Watergate reforms), except that there's more transparency."

Democrat response

Though Republicans moved first, Democrats and union allies are responding by creating Super PACs dedicated to re-electing President Barack Obama, taking control of Congress and exacting retribution for the anti-union measures adopted by Republican governors in Wisconsin, Ohio and elsewhere.

By law, Super PACs are not permitted to coordinate with campaigns, but political finance experts say Super PACs have quickly become an integral - if unofficial - part of many campaigns. The Super PACs often operate as un-policed "bad cops" of campaigns, allowing candidates to spend their own money on positive image-building and grassroots organization.

"Super PACs can have a much greater impact in House and Senate races, where an expenditure of a couple million dollars can have a major effect," said Anthony Corrado, a government professor at Colby College.

Democrats were slow to react to the brave new political world, but recently they have spent liberally on Super PACs to weaken tea party freshmen and other vulnerable Republican House members. Obama, who at first denounced Super PACs, recently reversed course and accepted help from a Super PAC staffed by former aides.

Even Linbeck - whose own group is a rare nonpartisan, non-ideological outfit - is concerned about the early impact of other Super PACs.

"I think the short-run impact is probably, on balance, negative," said Linbeck, whose father and namesake is a longtime GOP donor. "Because the first (Super PAC) movers were just more of the same, and because some of the biggest groups are taking advantage of a loophole in the law that allows for contributions to be made undisclosed, it has created a sense that shadowy forces are going to dominate American politics."

Still, the self-described "conservative communitarian" believes that groups like his could help grass-roots voters seize American politics back from special interests.

'A higher purpose'

"Why should partisans and ideologues be the only ones to use SuperPACs?" Linbeck asks. "Why not try to use this tool for a higher purpose, the restoration of self-governance and congressional accountability? "

The beneficiaries of Linbeck's involvement say it has been a help in their campaigns.

"I think 'levels the playing field' is a good expression," said Brian Shrive, campaign manager for Brad Wenstrup, an Iraq war veteran who defeated Rep. Jean Schmidt in Ohio's Republican primary. "In general, I guess, it's nicer to have a Super PAC supporting you than opposing you."